Water Supply & DistributionQuestion 17 of 360
When sizing water piping using the fixture unit method, why is the total demand in gpm always less than the simple sum of every fixture's peak flow?
a.Because it is statistically improbable that all fixtures operate simultaneously, so a diversity/demand factor is applied
b.Because fixture units already equal gpm exactly
c.Because the code ignores water closets
d.Because velocity is unlimited
Explanation
The fixture unit method applies a probability (diversity) factor recognizing that not all fixtures run at once, so estimated demand is less than the arithmetic sum of peak flows. Fixture units are not equal to gpm, water closets are counted, and velocity is limited, making the other options incorrect.
Law Reference: 2022 California Plumbing Code (CPC) §610.0Practice all 360 questions free — no signup required.
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